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A federal judge sentenced a former Arkansas judge Wednesday to five years in prison — a stiffer punishment than prosecutors recommended — after he admitted giving young male defendants lighter sentences in return for personal benefits that included sexual favours.

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In a 60 Minutes online exclusive, reporter Liz Hayes quizzed Australian Prime Minister Malcolm Turnbull on his relationship with the unpredictable Twitter aficionado and US president Donald Trump ahead of their meeting at the White House Friday.

US stops vetting Nauru refugees after Trump-Turnbull spat

US officials have stopped screening refugees for potential resettlement in the United States but will return to the Pacific atoll of Nauru to continue working toward a deal that President Donald Trump has condemned as "dumb", Immigration Minister Peter Dutton has said.

Mr Dutton would not say when US Department of Homeland Security officials would return to Nauru to conduct what Trump describes as "extreme vetting."

Trump made enhanced screening a condition for agreeing to honor an Obama administration deal to accept up to 1250 refugees refused entry into Australia. Australia pays Nauru and Papua New Guinea to keep more than 2000 asylum seekers — mostly from Iran, Afghanistan and Sri Lanka — in conditions condemned by rights groups.

The process of "extreme vetting" has yet to be explained.

US officials were sent to Nauru within days of the deal's announcement in November after the US presidential election. But they left this week with arrangements under a cloud.

"I don't have any comment to make in relation to when US officials will be on Nauru next," Dutton told reporters. "There have been officials there who have left ... in the last couple of days and we would expect other officials to be there in due course."

"But there is a lot of work being done at an officials level with people from my department and the Department of Homeland Security and the Department of State in the US, but it's not something that I have anything to comment on," he said.

Australia has determined that there are 1600 genuine refugees among 2077 asylum seekers on Papua New Guinea and Nauru. There could also be refugees among the 370 asylum seekers who came to Australia for medical treatment then took court action to prevent their return to the island camps.

About 1240 asylum seekers live in the camps while the remainder on the islands live in communities outside the fences.

Dutton could not say whether the 1600 refugees would pass the new US vetting regime.

"It's an issue for the United States under the agreement as to who they take and the way in which they conduct their vetting, so I don't have any comment in relation to the US process," Dutton said.

"Our desire is to get people off Nauru and Manus as quickly as possible," he added, referring to Papua New Guinea's Manus Island.

As of last week, Nauru held 1132 asylum seekers including women and children. The Manus facility houses only men.

Australia has said the "most vulnerable" refugees on Nauru would be given priority for US resettlement.

After committing to Prime Minister Malcolm Turnbull that he would honor the agreement, Trump tweeted that it was a "dumb deal."

Asked last week whether the deal would continue, Trump said: "We'll see what happens."